Agriculture is the backbone of the economy of Ethiopia where more than 85% of the population is engaged in and accounts for nearly 52% of the gross domestic product (GDP). Natural resources viz. land, water, vegetation, climate and topography and relief play significant role in the success of agriculture. Caused by population pressure, climate change and poor management of the natural resources, components of this sector have been threatened by chronic degradation, recurrent drought, shortage of skilled manpower and limited and improved technologies.
Efforts were made to combat natural resources degradation by generating technologies in soil and water conservation and re-afforestation, but the success has been gloomy because of different reasons. Emphasis to develop the water resource has been given top priority only in recent years. The potential for irrigated agriculture is estimated at more than 3.7 million hectares. The major direct threats to development of water resources for agriculture in Ethiopia are sedimentation of rivers and water reservoirs, reduced infiltration, recurrent drought etc. Ethiopian Agricultural Research Organization (EARO) has formulated a strategic research plan for the sector on its mandate area and also setting priority to generate technologies for the different agro-ecologies. Emphasis is given to water harvesting in situ and ex situ and management of irrigation water and drainage at all levels.
Agriculture accounts for more than 85% employment and 51.6% of the gross domestic product (GDP) and 90% of the export earnings (CSA 1999). Proper management of some of the natural resources is vital for healthy development of the sector.
The country's economic development policy aims at:
In recent years agricultural development has been highly affected by mismanagement of the natural resources. The Ethiopian highlands where the majority of the population lives have undulating topography and relief. Although stressed by high population density, the highlands have relatively better moisture, economic activities and infrastructure established. On the other hand the lowlands (<1500 metres above sea level, masl) have low and erratic rainfall, hence, low soil moisture, severe erosion, vector born diseases of humans and livestock. However, the lowlands have very high potential for the development of irrigated agriculture if water is available and infrastructure can be improved.
There is no reliable figure on the trend of forest cover in Ethiopia. However, as some historical sources indicate high forests might have once covered about 3540% of the total land area of the country (EPA/MEDaC 1997; EARO 2000a). According to Aklog (1990) deforestation was accelerated towards the beginning of the 20th century and in 1960 closed natural forest was estimated to cover only about 3.37%. It is believed that, in Ethiopia, agricultural activities must have started about 5000 years ago (EPA/MEDaC 1997) and wide spread deforestation started about 2500 years ago (Hurni 1988). FAO (1981) estimated the rate of deforestation in 1981 at 200 thousand hectares per year and it is expected that this figure will be much higher today and may continue so unless some alternative options are made available to the rural population. It has been estimated that high forests covered 16% of the land area in the early 1950s, 3.6% in the early 1980s (IUCN 1990) and only 2.7% in 1989 (EARO 2000a).
There are convincing indications of a downward spiral of forest resources degradation. Some of these are:
Some re-afforestation activities are underway but compared to the deforestation that is taking place it is only a small percentage and the majority of the replanted species are eucalyptus and cupressus with very low replanting of indigenous species. Re-afforestation is a planned activity with a targeted area to be covered each season whereas almost every household in the rural part of the country does cutting of trees as it wishes. Compared to the long years tree species take to reach a productive stage on degraded environment and against an increasing demand and the slow effort in re-afforestation the future for vegetation cover is gloomy.
As a result of increasing trend of population growth in the last six decades, (from 17 million in 1940 to 63 million in 2000) (EPA/MEDaC 1997), and increased exploitation of land resources, the balance of water resources has also been negatively affected. Although traditional small-scale irrigation practices existed in few places, scaling-up activities must have started since the 1960s. The traditional irrigation practices by the farmers have some setbacks:
However, farmers use simple tools available at their disposal. Today some small-scale irrigation plot owners use watering can or hose to water plants from the water source. Farmers growing some high cash crops and living near to market centres use small pumps and generators to raise water to higher points for gravity application.
Out of necessity, farmers adopt the principle of irrigation from their relatives and neighbours. Some farmers have adopted irrigation practice provided water is available.
However, furrow irrigation wastes water through seepage, evaporation by flowing a long distance. Adoption of concrete tubes or plastic hose can reduce the loss of water. Hand watering can also increase the efficiency of water management and reduce the incidence of disease spread from one plot to another.
In many places where irrigation water is managed under commercial plantation many perennial trees are observed near the canal or around the homestead and villages. These trees are planted for beautification of the landscape or for cooling and shading effect. However, the negative contribution of these perennial trees is their consumption of water is greater than the major crop produced. Renult et al. (2001) reported up to 43% of water consumption by the perennial trees compared to 22% by the crop in a tropical humid environment. Under the present circumstances of unlimited watering by furrow irrigation in the Awash Valley, the high evapo-transpiration observed and the high consumption by the non-intended perennial trees planners should reconsider traditional criteria for design and performance assessment.
Salinity affects over 11 million hectares of land in Ethiopia (Tadelle 1996). These naturally salt-affected areas are normally found in the dry lowlands and in the Rift Valley. The semi-arid climate of the Awash Valley has contributed to limited leaching by favouring accumulation of soluble salts in the soil. Most of the irrigated large-scale farms in the Awash Valley have been developed without giving due consideration to the delivery of irrigation water and provision of drainage facilities for safe disposal of the excess water.
The unique topography, type of soil, deforestation, intensive rainfall and low level of land management and the land use type practised have resulted in heavy runoff that induced soil erosion particularly in the northern and central highlands. Soil erosion is taking place all over the country but because of the effect of overpopulation on land that is already fragile (steep and mountainous), and mismanagement of the land itself, the northern and central highlands are the worst affected. Estimation made on the amount of soil that leaves the plot and deposited elsewhere or that leaves the country is unpredictable. This is expected because the Ethiopian topography, agro-ecology, type of soil associations, land use type etc. vary from one location to another. Kappel (1996) explained the source of variation in estimation as the complexity of land degradation that is taking place and the difficulty of measurement and the uncertainty of the extrapolation. However, the estimations made by the Ethiopian Highlands Reclamation Study (EHRS) and Soil Conservation Research Project (SCRP) are 100 t/ha with 1.8% loss of productive cropland (Constable and Belshaw 1989) and 42 t/ha with 2% loss of productive cropland per annum (Hurni 1988).
Except in few cases research in soil and water has not taken into consideration the catchment management. Hence, the effect of mismanagement of the catchment areas is already being felt in many communities in steep lands and where small-scale irrigation is in operation. Sedimentation of micro-dams is becoming a serious problem in the absence of an integrated watershed management practice. The issue may become the concern of many communities as development of small-scale irrigation continues. Catchment management is an important practice to adopt in soil and water conservation activities and agricultural water management.
A catchment area may comprise different soil types or agro-ecological conditions, depending on its extent and the physiographic and climatic conditions of the area. In Ethiopia, however, field orientation of agricultural experiments is on plot or single site basis. With the present situation of land degradation and possible expansion of small-scale irrigation in the highlands the adoption of watershed management approach becomes imperative. The country has also been more dependent on rain-fed agriculture but this is no more reliable. Under this approach each community will develop its own devices to conserve soil moisture in situ. Hence, research centres are advised to adopt the watershed management approach. Because of the advantages that watershed management approach offer, few regional states have now initiated several watershed management projects and depending on the success of these more of similar development projects will be initiated.
Farmers have a common perception regarding the cause for the decline in soil fertility. These are:
An example of the declining size of farms per household is indicated in Table 1. Throughout highland and midland Chiro woreda, in eastern Ethiopia, farmers were forced to move onto the valley slopes of 50 per cent gradient or more, despite a guideline to cultivate only lands with slopes below 35 per cent. This is the case in many other parts of the country (Thomas 1991; ICRA 1997; ICRA 1998; ICRA 1999-#2). The farmers are also forced to cultivate the same land year after year without fallowing. Among the cropped land cereals occupy about 90%. Hence, there is little option left to the farmer to improve soil fertility through crop rotation although resource rich farmers do practice some rotations and apply manure. Farmers with relatively small farmlands do not adopt soil conservation practices and this has an impact on soil fertility management and soil conservation, which will then cause land degradation as a result of unsustainable intensification of the land. The continuous cultivation has also aggravated soil erosion because the land where most of agricultural activities take place is steep in many areas. The method of land preparation has favoured erosion where essential nutrients have been washed off together with the soil. Severely degraded land has gone out of production particularly in steep slopes.
Braun et al. (1997) summarised and reported nutrient cycling between tree plantations and natural forests, few agroforestry tree species and forage species and the use of mineral fertilisers on cultivated crops. Under a situation where almost all cow dung is used as fuel, where most of the crop residues are used as animal feed, as fuel or construction material, the nutrient imbalance would be self-evident (Table 1)
Table 1. Total nutrient balance for land/water classes in the Ethiopian highlands.
| Land/moisture class | N kg ha-1 | P ka ha-1 | K kg ha-1 |
| Good rainfall | 52 |
7 |
33 |
| Uncertain rainfall | 35 | 5 | 24 |
| Problem rainfall | 41 | 4 | 24 |
It is believed that Ethiopia has a total volume of 109 billion cubic metres of surface water and about 2.6 billion cubic metres of ground water. (Abera and Deksios 2001). The western half of the country receives sustainable amount of precipitation and have many perennial rivers and streams while the precipitation is marginal in the eastern half of the country. Because of the progressive land degradation that is taking place at present the amount of water leaving the catchments carrying away soil with it must have increased ever than before. Hence, the amount of available water in situ has been reduced particularly in the eastern half of the country.
The Ethiopian plateau is the source of the Abay, Awash, Tekeze, Mereb, Baro-Akobo and Omo rivers that flow to the west and south-west. The Baro-Akobo basin is potentially the largest possible irrigable area (about 483 thousand hectares) although negligible area has been developed probably because of the large investment cost required and due to the distance from the central market for commercial agriculture. Awash River is the only river extensively used for commercial plantations of industrial and horticultural crops, in the Rift Valley. From the total irrigated area of about 161,125 ha, over 43% are found in the Awash River basin. The remaining potential for irrigated agriculture using the Awash River is estimated at 136,220 ha (Abera and Deksios 2001).
As a result of deforestation, soil erosion and over-exploitation by the population, the highlands are significantly degraded. This has resulted in increased acceleration of runoff along the slope thereby reducing water infiltration. Acceleration of runoff movement down the slope has also increased sedimentation in the downstream flat bottoms contributing to poor quality of water. Consequently, some small rivers, streams and springs have their volumes reduced or dried particularly during the dry season.
Social factors such as demographic pressure, land shortage, and social and cultural aspirations affect quality of soil and environment. These social-driven forces lead to several activities with major changes in soil and environmental characteristics such as deforestation, and new land development. Some may argue that trees increase evpo-transpiration during the dry season thereby reducing the amount of water received by the soil but in a steeping slope like in many parts of the Ethiopian highlands, trees can reduce the velocity and increase infiltration contributing to the ground more water recharge.
The general objective of the soil and water research programme is to improve the utilisation and minimise the degradation of natural resources for the sustained benefit of the nation at large and the farmers in particular. The goal of the strategy is therefore:
The importance of irrigation in agriculture is rapidly increasing to overcome the food deficiency to the rapidly growing population of the world (EARO 2000b). Ethiopia is already suffering from food shortage because of the increasing population and chronic drought occurrence in most parts of the eastern and northern part of the country. The estimated six million hectares under cereal production is under-productive while some of it could have been producing twice a year. At the same time Ethiopia is endowed with water resources, which could be easily tapped and used for irrigation.
This programme will handle basic soilcropwater relationships, water balance, agro-hydrology, irrigation, and drainage methods. Drainage of heavy clay soils will be an important component in the programme as a large area of the heavily populated land is covered by waterlogged soils. Reclamation of degraded soils and implementation of runoff farming for supplementary irrigation, efficient utilisation of water resources with special emphasis on the development of small-scale irrigation will be emphasised in the different agro-ecological zones (AEZs). Until now research on irrigation has focused at Werer Center in the midst of irrigated agriculture. However, it is still deficient in skilled manpower and facilities compared to the service it renders to irrigated agriculture in the country. The research on agricultural water management at Werer may not cover the interest of the highlands or other potentially irrigable areas in the lowlands because of differences in agro-ecology and soils.
The current government policy for economic development pathway to industrialisation is through the development of the agriculture sector. There are some obstacles facing the development of the water sector such as land tenure and land use issues, and water basin development vs. ethnic bound development planning. However, there are some positive sides, too, regarding agricultural development.
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